updated deprecated styles

[rachejazz]

Ran into couple of errors

• While using sh. Cannot recognise [[

+ [[ -f /etc/ssh/moduli ]]
./harden.sh: 16: [[: not found

• Using deprecated find flags:

+ find / -xdev -type d -perm +0002 -exec chmod o-w {} +
find: invalid mode ‘+0002’

+ find /bin /etc /lib /sbin /usr -xdev -type f -a -perm +4000 -delete
find: invalid mode ‘+4000’

this is happening because find has deprecated +mode. From man page of find: